San Francisco 49ers linebacker Reuben Foster was arrested this weekend for domestic violence and possession of an assault weapon … making this his 2nd arrest in a month.

According to the Los Gatos Monte Sereno Police Department … Foster was arrested Sunday morning after cops responded to a welfare check and possible disturbance call. They say the 49ers star was arrested without incident.

He was booked on three separate charges — domestic violence, threats and possession of an assault weapon. No further details were immediately available.

Foster was also arrested in Alabama about a month ago to the day for marijuana possession.

The 49ers responded by saying … “The San Francisco 49ers organization is aware of the report regarding Reuben Foster. We take matters of this nature seriously and are gathering all pertinent information.”